Forklift type AGV trolley for carrying battery pack

Abstract

The invention relates to the technical field of battery carrying and conveying, in particular to a forklift type AGV trolley for carrying a battery pack, which comprises a trolley body and a pallet fork arranged above the trolley body, the pallet fork is connected with the top of the trolley body through an electric track, universal trundles are mounted at the bottom of the front end of the pallet fork, a lifting plate is arranged above the pallet fork, and the lifting plate is connected with the top of the trolley body. An air pressure lifting structure is connected between the lifting plate and the pallet fork, and a plurality of groups of positioning plates are distributed on the lifting plate; self-adaptive positioning of a non-flat structure at the bottom of the battery pack is achieved, the hidden danger of rollover of a traditional AGV is avoided, multiple sets of independent positioning plates on the lifting plate are matched with a hydraulic lifting structure, all sets of positioning plates can move upwards according to the protrusion and depression difference of the bottom of the battery pack, finally multi-point uniform supporting is formed, and the effective supporting area is greatly increased; the problem of center-of-gravity shift caused by local contact of traditional fixed prongs is solved, the risk of battery pack rollover during AGV starting and stopping or steering is reduced, and the AGV is suitable for carrying battery packs of multiple sizes and complex bottom structures.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery carrying and conveying, in particular to a forklift AGV for carrying battery packs. BACKGROUND

[0002] In the field of new energy vehicle manufacturing and energy storage power station construction, battery packs are the core energy unit, and carrying efficiency and safety are extremely high. At present, forklift AGVs have gradually replaced manual forklifts and become the mainstream equipment for carrying battery packs due to their advantages of automatic operation and flexible path. However, the structure of battery packs needs to be strictly adapted to the installation requirements of different vehicle models or energy storage equipment: on the one hand, the installation space of different vehicle models (such as passenger cars, commercial vehicles, and special operation vehicles) and energy storage equipment varies greatly, resulting in various sizes of battery packs; on the other hand, to meet the requirements of electrical connection, thermal management, and mechanical fixation, the bottom of the battery pack often integrates non-flat structures such as pole protrusions and cooling pipe interfaces, and some also have local depressions or stepped protrusions, with complex and irregular bottom shapes.

[0003] The existing forklift AGVs have fixed-size flat tines or rigid trays as the carrying mechanism, without considering the non-flat characteristics and size diversity of the bottom of the battery pack. When carrying battery packs with protrusions on the bottom, only partial contact occurs between the two, resulting in a significant reduction in effective support area, which leads to a shift in the center of gravity of the battery pack. When the AGV starts, stops, or turns, the inertial force easily causes the battery pack to tilt and overturn, which may cause damage to the shell and the battery cells, and even lead to safety accidents due to electrolyte leakage and electrode short circuit. Therefore, a forklift AGV for carrying battery packs is proposed to adapt to the carrying of battery packs with different bottom structures, improve the carrying stability of the AGV, and solve the problem of easy overturning. SUMMARY

[0004] To solve the problems in the prior art, the present application provides a forklift AGV for carrying battery packs, which is convenient for adapting to the carrying of battery packs with different bottom structures, improves the carrying stability of the AGV, and solves the problem of easy overturning.

[0005] The technical scheme adopted by the present application to solve its technical problems is a forklift type AGV trolley for carrying battery packs, comprising a vehicle body, and a fork arranged above the vehicle body, the fork is connected with the top of the vehicle body through an electric track, a universal wheel is installed at the front end of the fork, a lifting plate is arranged above the fork, a gas pressure lifting structure is connected between the lifting plate and the fork, a plurality of sets of positioning plates are distributed on the lifting plate, a hydraulic lifting structure is connected between the positioning plate and the lifting plate, the rear end of the fork is connected with the vehicle body through a multi-stage air supply cylinder, a pressing valve is arranged on one side of the multi-stage air supply cylinder and communicated with the multi-stage air supply cylinder, a gas-liquid driving assembly is connected above the end of the vehicle body away from the universal wheel and communicated with the pressing valve, and the gas-liquid driving assembly is communicated with the gas pressure lifting structure and the hydraulic lifting structure through pipelines.

[0006] Specifically, the multi-stage air supply cylinder is filled with high-pressure gas, the movable end of the multi-stage air supply cylinder is connected with the rear end of the fork through a pressing plate, and the pressing plate corresponds to the pressing valve.

[0007] Specifically, the gas-liquid driving assembly comprises a cylinder vertically arranged on the vehicle body, a vertically arranged hydraulic cylinder is fixedly connected to the upper end of the cylinder, the lower end of the hydraulic cylinder is communicated with the inside of the cylinder, a driving plate is sealingly and slidably connected to the lower end of the hydraulic cylinder, a pressing spring is fixedly connected between the driving plate and the inner wall of the hydraulic cylinder, the hydraulic cylinder is filled with hydraulic oil, the cylinder is communicated with the pressing valve through an air inlet joint and a pipeline, the gas pressure lifting structure is communicated with the cylinder through a gas supply pipeline with a one-way valve, and the hydraulic cylinder is communicated with the hydraulic lifting structure through an oil supply pipeline with a one-way valve.

[0008] Specifically, one side of the cylinder is provided with a horizontally arranged first multi-way valve, the valve rod of the first multi-way valve corresponds to the pressing plate; the gas pressure lifting structure is communicated with the first multi-way valve through a gas return pipeline, and the gas outlet end of the first multi-way valve is communicated with the multi-stage air supply cylinder through a pipeline.

[0009] Specifically, a horizontally arranged second multi-way valve is arranged behind the side of the first multi-way valve away from the fork, the valve rod of the second multi-way valve corresponds to the pressing plate; the hydraulic lifting structure is communicated with the liquid inlet end of the second multi-way valve through an oil return pipeline, and the liquid outlet end of the second multi-way valve is communicated with the hydraulic cylinder through a pipeline.

[0010] Specifically, the gas pressure lifting structure comprises a plurality of sets of mounting holes arranged on the fork, a cylinder is fixedly connected in the mounting hole, a piston plate is sealingly and slidably connected in the cylinder, a vertically arranged piston rod is fixedly connected to the upper surface of the piston plate, a first return spring is fixedly connected between the upper surface of the piston plate and the inner wall of the cylinder, the upper end of the piston rod is fixedly connected with the lower surface of the lifting plate, and the cylinder is communicated with the cylinder through a gas supply pipeline with a one-way valve.

[0011] Specifically, the hydraulic lifting structure comprises a plurality of groups of driving rods corresponding to the piston rods, the upper ends of the driving rods are fixedly connected with the lower surfaces of the positioning plates, the piston rods are provided with piston cavities, the sealing plates are sealingly and slidably connected in the piston cavities, and the second return springs are fixedly connected between the lower surfaces of the sealing plates and the inner walls of the piston cavities.

[0012] The upper surfaces of the lifting plates are provided with sliding holes in communication with the interiors of the piston cavities, the lower ends of the driving rods pass through the sliding holes and are fixedly connected with the upper surfaces of the sealing plates, and the piston cavities are in communication with the hydraulic cylinders through oil supply pipelines provided with one-way valves.

[0013] Specifically, the upper surfaces of the positioning plates are detachably connected with the elastic rubber pads.

[0014] Specifically, the two ends of the positioning plates are provided with the elastic supporting rollers.

[0015] The beneficial effects of the present application are as follows:

[0016] (1) The fork truck AGV trolley for carrying the battery pack can realize self-adaptive positioning of the non-flat structure at the bottom of the battery pack, solve the hidden danger of the traditional AGV rollover, and through the cooperation of the multiple groups of independent positioning plates on the lifting plate and the hydraulic lifting structure, each group of positioning plates can be lifted according to the differences of the protrusions and depressions at the bottom of the battery pack, and finally, multiple-point uniform support is formed, the effective support area is greatly increased, the problem of gravity deviation caused by the local contact of the traditional fixed fork teeth is solved, the risk of the battery pack rollover when the AGV starts or stops or turns is reduced, and the battery pack carrying of the battery pack with a complex bottom structure is adapted.

[0017] (2) The fork truck AGV trolley for carrying the battery pack can realize the timing power conversion of positioning first and lifting later through the gas-liquid driving assembly, after the multi-stage gas supply cylinder is triggered, the high-pressure gas preferentially drives the hydraulic lifting structure to complete the positioning plate and the bottom of the battery pack, and then drives the air pressure lifting structure to drive the whole to move up, the timing avoids the hard contact between the battery pack and the forks, protects the fragile parts such as the bottom pole and the pipeline interface, and the air pressure lifting ensures the uniform stress of the battery pack, and guarantees the structural and electrical safety in the process of carrying the battery pack.

[0018] (3) The fork truck type AGV trolley for carrying the battery pack, when the fork is reset, the first multi-way valve triggers the high-pressure gas in the air pressure lifting structure to flow back to the multi-stage gas supply cylinder, realizes power recovery and reuse, reserves high-pressure gas for next carrying; when different specifications of battery packs need to be switched, the second multi-way valve triggers the hydraulic oil in the hydraulic lifting structure to flow back to the hydraulic cylinder, drives the positioning plate to drop to the initial reference height flush with the lifting plate, ensures that each group of positioning plates starts to adhere from the same reference when carrying new specifications of batteries, avoids the support deviation caused by the initial height difference, does not need manual adjustment of the bearing mechanism, and can realize continuous carrying of different specifications of battery packs, greatly shortens the carrying cycle, and improves the continuity and adaptability of automatic operation. BRIEF DESCRIPTION OF DRAWINGS

[0019] The application will be further described below in combination with the drawings and examples.

[0020] Figure 1 is the axonometric view of the application;

[0021] Figure 2 is another axonometric view of the application;

[0022] Figure 3 is a schematic view of the fork bottom structure of the application;

[0023] Figure 4 is a side view of the application;

[0024] Figure 5 is the A area enlarged view of Figure 2 ; is the A area enlarged view of

[0025] Figure 6 is a schematic view of the cylinder and hydraulic cylinder cross-section structure of the application;

[0026] Figure 7 is a schematic view of the cylinder cross-section structure of the application;

[0027] Figure 8 is a schematic view of the fork reset initial state of the application;

[0028] Figure 9 is a schematic view of the structure when the elastic support roller contacts the bottom of the battery pack;

[0029] In the figure: 1, vehicle body; 2, fork; 3, electric track; 4, universal caster; 5, lifting plate; 6, positioning plate; 7, multi-stage air supply cylinder; 8, pressing valve; 9, extrusion plate; 10, cylinder; 11, hydraulic cylinder; 12, driving plate; 13, extrusion spring; 14, air inlet joint; 15, first multi-way valve; 16, second multi-way valve; 17, mounting hole; 18, cylinder; 19, piston plate; 20, piston rod; 21, first return spring; 22, driving rod; 23, piston cavity; 24, sealing plate; 25, second return spring; 26, sliding hole; 27, elastic rubber pad; 28, elastic support roller. DETAILED DESCRIPTION

[0030] In order to make the technical means, creative features, purposes and effects of the present application easy to understand, the present application will be further described below in conjunction with specific embodiments.

[0031] In order to facilitate the adaptation of different bottom structure battery pack carrying, improve the AGV carrying stability, solve the problem of easy to overturn, as an embodiment of the present application, as shown in the figure, Figures 1-3 A fork truck AGV for carrying battery pack, comprising a vehicle body 1, and a fork 2 arranged above the vehicle body 1, the fork 2 is connected with the top of the vehicle body 1 through an electric track 3, the front end of the fork 2 is provided with a universal caster 4, a lifting plate 5 is arranged above the fork 2, a pneumatic lifting structure is connected between the lifting plate 5 and the fork 2, a plurality of positioning plates 6 are distributed on the lifting plate 5, a hydraulic lifting structure is connected between the positioning plates 6 and the lifting plate 5, the rear end of the fork 2 is connected with the vehicle body 1 through a multi-stage air supply cylinder 7, one side of the multi-stage air supply cylinder 7 is provided with a pressing valve 8 communicated with the multi-stage air supply cylinder 7, the end of the vehicle body 1 away from the universal caster 4 is connected with a gas-liquid driving assembly communicated with the pressing valve 8, the gas-liquid driving assembly is communicated with the pneumatic lifting structure and the hydraulic lifting structure through pipelines.

[0032] In use, the vehicle body 1 is driven to move to the preset parking area of the battery pack to be carried, when the vehicle body 1 is positioned, the electric track 3 at the top of the vehicle body 1 is started to drive the fork 2 to horizontally extend along the track direction, in this process, the multi-stage air supply cylinder 7 is continuously extruded due to the extension action of the fork 2, the horizontal thrust of the multi-stage air supply cylinder 7 is formed when the fork 2 extends, so that the multi-stage air supply cylinder 7 is retracted, at the same time, the universal caster 4 moves synchronously with the fork 2, which can assist to support the weight after the fork 2 extends, avoiding the fork 2 from sagging, shaking or deviating due to the too long extension length, ensuring that the fork 2 always extends smoothly along the horizontal direction;

[0033] When the forks 2 are extended to the preset position by the electric track 3, that is, the forks 2 are located directly below the battery pack to be carried, the extrusion force of the rear end of the forks 2 on the multi-stage air supply cylinder 7 reaches a threshold value, and at the same time, the pressing valve 8 on one side of the multi-stage air supply cylinder 7 is extruded, and the pressing valve 8 is opened after being extruded. At this time, the gas stored in the multi-stage air supply cylinder 7 is delivered to the gas-liquid driving assembly through the pipeline connected with the pressing valve 8. After receiving the gas power from the multi-stage air supply cylinder 7, the gas-liquid driving assembly preferentially converts the gas pressure into hydraulic driving energy, and transmits the driving energy to the hydraulic lifting structure between the forks 2 and the lifting plate 5 through a special communication pipeline. The hydraulic lifting structure is started under the action of the hydraulic driving energy, and drives the several groups of positioning plates 6 distributed on the lifting plate 5 to move upward in the vertical direction. Since the positioning plates 6 are distributed in multiple groups, they can be fitted with different areas of the bottom of the battery pack according to the uneven structure of the bottom of the battery pack, that is, the positioning plates 6 corresponding to the protruding area of the bottom may be contacted first, the positioning plates 6 corresponding to the recessed area continue to move upward to contact, and finally the upper surfaces of all the positioning plates 6 are in close contact with the bottom of the battery pack, and the force of each group of positioning plates 6 is balanced, completing the preliminary support and positioning of the battery pack.

[0034] When all the positioning plates 6 are in close contact with the bottom of the battery pack, the positioning plates 6 are limited by the reaction force of the weight of the battery pack and cannot continue to move upward. At this time, the gas-liquid driving assembly converts the gas power into gas pressure driving energy, which is transmitted to the gas pressure lifting structure between the forks 2 and the lifting plate 5 through another set of special communication pipelines. The gas pressure lifting structure is started under the action of the gas pressure driving energy, and drives the lifting plate 5 connected thereto to move upward in the vertical direction. Since the positioning plates 6 are in close contact with the bottom of the battery pack and form a stable support, the upward movement of the lifting plate 5 is synchronized to the battery pack through the positioning plates 6, driving the battery pack to move upward together with the lifting plate 5. The lifting action continues until the bottom of the battery pack is completely separated from the original parking plate, and a sufficient safety gap is reserved between the bottom of the battery pack and the parking plate. At this time, the lifting action stops, and the entire battery pack lifting process is completed.

[0035] During the entire process, the first fitting and then lifting of the positioning plates 6 can avoid direct hard contact of the battery pack with the forks 2, reducing the extrusion damage to the vulnerable structures such as the bottom pole and pipeline interface of the battery pack. The multi-point contact of the multiple positioning plates 6 with the bottom of the battery pack greatly increases the effective support area, avoiding the center of gravity deviation caused by the local contact of the traditional prongs. At the same time, the gas pressure lifting structure drives the lifting plate 5 to move upward stably as a whole, and the positioning plates 6 as the intermediate force transmission medium can ensure that the battery pack is evenly stressed and does not tilt due to local excessive stress, effectively reducing the risk of the battery pack tipping over when the AGV starts, stops or turns.

[0036] For example, Figure 2 , Figure 5As shown, the present invention also includes a multi-stage air supply cylinder 7 filled with high-pressure gas, the movable end of the multi-stage air supply cylinder 7 being connected to the rear end of the fork 2 via a pressing plate 9, and the pressing plate 9 corresponding to the pressing valve 8.

[0037] When in use, before the AGV trolley starts the handling operation, the multi-stage air supply cylinder 7 is in a naturally extended state. When the vehicle body 1 is positioned under the battery pack to be transported, the electric rail 3 on the top of the vehicle body 1 is activated, driving the forks 2 to extend horizontally along the rail. The extrusion plate 9 extrudes the moving end of the multi-stage air supply cylinder 7. During this process, the high-pressure gas inside the multi-stage air supply cylinder 7 is further compressed due to the reduction in the volume of the cylinder 18, and the gas pressure increases synchronously, reserving sufficient power for the subsequent triggering of the pressing valve 8.

[0038] As the forks 2 continue to extend, the compression plate 9 moves synchronously with the moving end of the multi-stage air supply cylinder 7 until the forks 2 extend to the preset position. At this time, the movement distance of the compression plate 9 reaches the threshold, and the compression plate 9 is in complete contact with the trigger end of the pressing valve 8, causing the pressing valve 8 to open. At this time, the high-pressure gas compressed inside the multi-stage air supply cylinder 7 is directionally delivered to the pneumatic-hydraulic drive assembly on the vehicle body 1, providing a power source for the subsequent positioning plate 6 to fit and the lifting plate 5 to lift.

[0039] For example, such as Figure 2 , Figure 6 As shown, the present invention further includes a cylinder 10 vertically mounted on the vehicle body 1, a vertically mounted hydraulic cylinder 11 fixedly connected to the upper end of the cylinder 10, the lower end of the hydraulic cylinder 11 communicating with the interior of the cylinder 10, a drive plate 12 being slidably connected to the lower end of the hydraulic cylinder 11, a compression spring 13 being fixedly connected between the drive plate 12 and the inner wall of the hydraulic cylinder 11, the hydraulic cylinder 11 being filled with hydraulic oil, the cylinder 10 being connected to a pressing valve 8 via an air inlet connector 14 and a pipeline, the pneumatic lifting structure being connected to the cylinder 10 via an air supply pipeline with a one-way valve, and the hydraulic cylinder 11 being connected to the hydraulic lifting structure via an oil supply pipeline with a one-way valve.

[0040] In use, when the press valve 8 is triggered to open by the pressing plate 9, the high-pressure gas stored in the multi-stage gas supply cylinder 7 is delivered to the inside of the barrel 10 through the gas inlet joint 14. At this time, the gas pressure in the barrel 10 rises rapidly. Since the force area and movement resistance of the driving plate 12 are smaller than the starting resistance of the gas pressure lifting structure, the high-pressure gas acts on the lower surface of the driving plate 12. Under the continuous pressure of the high-pressure gas, the driving plate 12 slides upward along the inner wall of the hydraulic cylinder 11. In this process, the compression spring 13 is compressed, and the elastic force is stored at the same time. At the same time, the upward movement of the driving plate 12 will cause the hydraulic oil in the hydraulic cylinder 11 to be squeezed. Since the hydraulic cylinder 11 is connected to the hydraulic lifting structure through the oil supply pipeline with a one-way valve, and the one-way valve only allows the hydraulic oil to flow from the hydraulic cylinder 11 to the hydraulic lifting structure in one direction, the compressed hydraulic oil is delivered to the hydraulic lifting structure along the oil supply pipeline, providing hydraulic power for the lifting of the positioning plate 6.

[0041] The positioning plate 6 corresponding to the raised area of the bottom of the battery pack first contacts the raised surface, and is limited by the reaction force of the raised surface. This group of positioning plates 6 stops moving upward, and the positioning plate 6 corresponding to the recessed area continues to move upward under the continuous pressure of the hydraulic oil until the upper end surface of the positioning plate 6 is tightly attached to the bottom surface of the recessed area. Finally, the upper surfaces of all positioning plates 6 are attached to different areas of the bottom of the battery pack, and the forces of each group of positioning plates 6 are balanced, completing the self-adaptive positioning and preliminary support of the battery pack.

[0042] When all the positioning plates 6 are completely attached to the bottom of the battery pack, the positioning plates 6 are limited by the reaction force of the weight of the battery pack and cannot continue to move upward. The hydraulic oil in the hydraulic cylinder 11 cannot continue to flow out, and the driving plate 12 is reversely limited by the hydraulic oil and cannot continue to slide upward. At this time, the high-pressure gas pressure in the barrel 10 continues to rise. When the gas pressure exceeds the starting threshold of the gas supply pipeline with a one-way valve, the high-pressure gas is delivered to the gas pressure lifting structure along the gas supply pipeline. The one-way valve prevents backflow to ensure stable gas pressure. After the high-pressure gas enters the gas pressure lifting structure, the driving lifting plate 5 moves upward. The upward movement of the lifting plate 5 is transmitted to the battery pack through the positioning plate 6 synchronously. The driving battery pack moves smoothly along the vertical direction with the lifting plate 5. The battery pack continues to lift until the bottom of the battery pack is completely separated from the original parking plate, and a sufficient safety gap is reserved between the bottom and the parking plate to avoid friction damage during the lifting process. At this time, the gas pressure lifting structure stops working, and the whole gas-liquid driving process is completed. The risk of battery pack deviation and overturning caused by direct lifting is effectively avoided, ensuring that the battery pack is accurately supported by multiple positioning plates 6 before lifting, and improving the safety and accuracy of the lifting operation.

[0043] For example, Figure 1 , Figure 2As shown, the application also includes that one side of the cylinder 10 is provided with a horizontally arranged first multi-way valve 15, the valve rod of the first multi-way valve 15 corresponds to the extrusion plate 9; the air pressure lifting structure is communicated with the first multi-way valve 15 through the back gas pipeline, and the gas outlet end of the first multi-way valve 15 is communicated with the multi-stage gas supply cylinder 7 through the pipeline.

[0044] In use, when the battery pack is lifted into place by the air pressure lifting structure, and needs to be transported to the designated position, the electric track 3 at the top of the vehicle body 1 is started, and the fork 2 which has completed the supporting task retreats horizontally after the horizontal reset of the track, in this process, the extrusion plate 9 drives the gas cylinder 18 to extend, at the same time, the extrusion plate 9 is separated from the contact with the pressing valve 8, the pressing valve 8 is closed under the action of its own reset structure, cutting off the gas passage between the multi-stage gas supply cylinder 7 and the cylinder 10, to avoid the cross flow when the subsequent gas backflow;

[0045] When the fork 2 retreats to the appropriate area above the vehicle body 1, the extrusion plate 9 is in full contact with the valve rod of the first multi-way valve 15, and exerts a horizontal extrusion force on the valve rod, so that the first multi-way valve 15 is opened, the high-pressure gas stored in the air pressure lifting structure for supporting the lifting plate 5 and the battery pack before, along the back gas pipeline, the first multi-way valve 15, is backflowed to the inside of the multi-stage gas supply cylinder 7, to supplement the gas for the multi-stage gas supply cylinder 7, and restore its initial high-pressure state, to ensure the power reserve for the next time of carrying;

[0046] On the other hand, the gas pressure in the air pressure lifting structure gradually decreases with the backflow, and at the same time, relying on the weight of the battery pack, the lifting plate 5 moves down along the vertical direction stably, synchronously driving the battery pack to move downward, while the hydraulic lifting structure cannot reverse the flow of the hydraulic oil in the hydraulic cylinder 11 due to the pressure maintaining effect of the one-way valve in the oil supply pipeline, and the positioning plate 6 still maintains the close contact state with the bottom of the battery pack, to avoid the deviation or shaking of the battery pack during the descending process; after the lifting plate 5 continuously moves down to the safe height, the gas in the air pressure lifting structure is basically backflowed, and the lifting plate 5 stops moving downward, at this time, the battery pack still maintains the stable contact through the positioning plate 6 of the hydraulic lifting structure, the vehicle body 1 starts the moving function, and transports the battery pack to the designated position along the preset path, to complete the reset and transportation links of the whole carrying process, and improve the overall carrying efficiency;

[0047] When the battery pack is carried to the designated position, the artificial or mechanical arm takes the battery pack from the positioning plate 6, and the positioning plate 6 still maintains the height position matched with the battery of the specification due to the pressure maintaining of the hydraulic lifting structure by the one-way valve of the oil supply pipeline. After the lifting plate 5 is reset, the vehicle body 1 starts the moving function and drives to the next storage area of the battery to be carried along the preset path. Since the battery to be carried is consistent with the previous specification and shape, the vehicle body 1 needs to be moved to the front of the battery. The electric track 3 is started to drive the fork 2 to horizontally extend along the track, and the rear end of the fork 2 is pressed again by the extrusion plate 9 to compress the movable end of the multi-stage gas supply cylinder 7. The high-pressure gas in the multi-stage gas supply cylinder 7 is compressed, and the pressure is increased. When the fork 2 extends to the preset position below the battery of the specification, the extrusion plate 9 triggers the press valve 8 to open, and the high-pressure gas in the multi-stage gas supply cylinder 7 is directionally delivered to the cylinder 10 through the pipeline. After the high-pressure gas enters the cylinder 10, since the positioning plate 6 of the hydraulic lifting structure is at the height matched with the battery of the specification, and the bottom structure of the battery is consistent, the hydraulic oil does not need to be additionally delivered. At this time, the cylinder 10 directly delivers the high-pressure gas to the gas pressure lifting structure through the gas supply pipeline, pushes the piston plate 19 and the piston rod 20 to move upward, and drives the lifting plate 5 to synchronously rise. During the upward movement of the lifting plate 5, the positioning plate 6 directly contacts the preset contact point of the bottom of the battery due to the height matching, and lifts the battery stably together with the lifting plate 5 to separate from the supporting plate, and completes the lifting action of the second carrying. After the battery is lifted to the position, the electric track 3 drives the fork 2 to reset and retreat, the vehicle body 1 carries the battery along the path to the target position, and the unloading process is repeated, the positioning plate 6 is omitted, the carrying cycle is shortened, the operation process is simplified, and the efficiency is improved.

[0048] As shown in Figure 1 、 Figure 2 , the present application further comprises that the second multi-way valve 16 is horizontally arranged at the rear side away from the fork 2 of the first multi-way valve 15, and the valve rod of the second multi-way valve 16 corresponds to the extrusion plate 9. The hydraulic lifting structure is communicated with the liquid inlet end of the second multi-way valve 16 through the oil return pipeline, and the liquid outlet end of the second multi-way valve 16 is communicated with the hydraulic cylinder 11 through the pipeline.

[0049] In use, when the current specification battery pack is unloaded, and needs to be switched to a different specification or size of the battery pack for handling, due to the need to adapt to the new specification battery, further reset of the hydraulic lifting structure is needed, continue to start the electric track 3, drive the fork 2 to retreat a preset distance away from the direction of the battery to be transported, because the second multi-way valve 16 is horizontally arranged on the side of the first multi-way valve 15 away from the fork 2, and its valve rod is pre-set corresponding to the position of the extrusion plate 9, when the extrusion plate 9 further retreats with the fork 2, it will extrude the valve rod of the second multi-way valve 16, after the second multi-way valve 16 is opened, the hydraulic oil in the hydraulic lifting structure returns to the inside of the hydraulic cylinder 11 through the oil return pipeline and the second multi-way valve 16, replenishes the hydraulic oil reserve in the hydraulic cylinder 11, and restores the initial liquid level; with the continuous return of the hydraulic oil, eventually the positioning plate 6 is lowered from the height of the previous specification battery to the initial position flush with the upper surface of the lifting plate 5, when the new specification battery is adapted, each group of positioning plate 6 can start from the same reference height and be attached upward, avoiding the attachment deviation caused by the initial height difference, and further improving the support stability during the new battery handling;

[0050] After the positioning plate 6 is completely reset, the electric track 3 is started to drive the fork 2 to move, which synchronously moves the extrusion plate 9, so that it gradually separates from the extrusion contact with the valve rod of the second multi-way valve 16 and the valve rod of the first multi-way valve 15. After the two groups of multi-way valves lose the extrusion force, the oil return passage and the gas return passage are cut off, and the gas-liquid circuit remains in a sealed state, so that the vehicle body 1 can be directly moved to the position of the next group of battery packs to be transported, thereby preparing for the subsequent handling process.

[0051] As shown in Figure 1 、 Figure 3 、 Figure 4 、 Figure 7 illustrated, the present application further comprises a plurality of mounting holes 17 arranged on the fork 2, a gas cylinder 18 fixedly connected in the mounting hole 17, a piston plate 19 sealingly and slidably connected in the gas cylinder 18, a vertical piston rod 20 fixedly connected to the upper surface of the piston plate 19, a first reset spring 21 fixedly connected between the upper surface of the piston plate 19 and the inner wall of the gas cylinder 18, the upper end of the piston rod 20 is fixedly connected with the lower surface of the lifting plate 5, and the gas cylinder 18 is communicated with the cylinder body 10 through the gas supply pipeline with a one-way valve.

[0052] In use, after the hydraulic lifting structure drives the positioning plate 6 to be completely in contact with the bottom of the battery pack, and the positioning plate 6 is restricted from moving upward due to the reaction force of the battery pack weight, the high-pressure gas accumulated inside the cylinder 10 of the pneumatic-hydraulic drive component is directionally delivered to the cylinder 18 of the pneumatic lifting structure through the air supply pipeline with a one-way valve. The high-pressure gas pushes the piston plate 19 in the cylinder 18, overcoming the elastic force of the first return spring 21 and sliding upward. The piston plate 19 drives the piston rod 20 to move upward synchronously. The top of the piston rod 20 pushes the lifting plate 5 to move upward. The upward movement of the lifting plate 5 drives the battery pack to move upward synchronously with the lifting plate 5 through the positioning plate 6, until the bottom of the battery pack is completely separated from the initially placed support plate. At this time, the pressure in the cylinder 18 and the elastic force of the first return spring 21 reach dynamic equilibrium, the lifting action stops, and the battery lifting process is completed.

[0053] The electric track 3 on the top of the vehicle body 1 is activated, driving the forks 2, which have completed their support task, to horizontally reset and retract along the track. After the forks 2 retract to the designated position, the compression plate 9 triggers the first multi-way valve 15. The cylinder 18 is connected to the multi-stage air supply cylinder 7 through the return air pipeline. The high-pressure gas in the cylinder 18 is discharged back to the multi-stage air supply cylinder 7 through the return air pipeline and the first multi-way valve 15, replenishing the gas in the multi-stage air supply cylinder 7 to restore its initial high-pressure energy storage state. The pressure in the cylinder 18 decreases, and at the same time, relying on the weight of the battery pack, the lifting plate 5 is lifted. The battery pack moves downwards in a vertical direction, and the first return spring 21 pushes the piston plate 19 downwards to reset, causing the piston rod 20 and the lifting plate 5 to fall back to their initial positions. When the gas in the cylinder 18 has finished flowing back, the lifting plate 5 stops moving downwards. At this time, the battery pack is still stably attached by the positioning plate 6 of the hydraulic lifting structure. The vehicle body 1 starts the moving function and transfers the battery pack to the designated position along the preset path, completing the reset and transfer links of the entire handling process and improving the overall handling efficiency.

[0054] It should be noted that the distance between the first multi-way valve 15 and the second multi-way valve 16 is small to avoid excessive compression and damage to the valve stem of the first multi-way valve 15 when the extrusion plate 9 extrudes the second multi-way valve 16; and an elastic pad can be installed at the front end of the valve stem of the first multi-way valve 15 to reduce wear and provide elastic support.

[0055] For example, such as Figure 1 , Figure 4 , Figure 7 As shown, the present invention also includes a hydraulic lifting structure comprising a plurality of drive rods 22 corresponding to the piston rod 20. The upper end of the drive rod 22 is fixedly connected to the lower surface of the positioning plate 6. The piston rod 20 is provided with a piston cavity 23. A sealing plate 24 is slidably connected in the piston cavity 23. A second return spring 25 is fixedly connected between the lower surface of the sealing plate 24 and the inner wall of the piston cavity 23.

[0056] The upper surface of the lifting plate 5 is provided with a sliding hole 26 in communication with the inside of the piston cavity 23, the lower end of the driving rod 22 passes through the sliding hole 26 and is fixedly connected with the upper surface of the sealing plate 24, and the piston cavity 23 is in communication with the hydraulic cylinder 11 through an oil supply pipeline with a one-way valve.

[0057] In use, when the valve 8 is pressed to be opened, the high-pressure gas in the multi-stage gas supply cylinder 7 pushes the driving plate 12 of the gas-liquid driving assembly to move upwards, the hydraulic oil in the hydraulic cylinder 11 is extruded and then flows into the piston cavity 23 of the piston rod 20 through the oil supply pipeline with a one-way valve, the oil liquid thrust overcomes the elastic force of the second reset spring 25, pushes the sealing plate 24 to slide upwards along the piston cavity 23, and the sealing plate 24 drives the driving rod 22 and the positioning plate 6 to move upwards synchronously, and finally a plurality of positioning plates 6 are differentiated from the driving rod 22 and move upwards, adhere to the uneven structure at the bottom of the battery pack, and complete the adaptive support;

[0058] When it is needed to reset the positioning plate 6 to switch different specifications of battery packs, the electric track 3 drives the fork 2 to further retreat, the pressing plate 9 is in contact with the valve rod of the second multi-way valve 16 and is extruded, the second multi-way valve 16 is opened, the piston cavity 23 is in communication with the hydraulic cylinder 11 through the oil return pipeline, the hydraulic oil in the piston cavity 23 flows back to the hydraulic cylinder 11 through the oil return pipeline and the second multi-way valve 16 under the action of the pressure difference and the elastic force of the second reset spring 25, the sealing plate 24 moves downwards with the oil liquid, drives the driving rod 22 and the positioning plate 6 to fall back synchronously, and until the positioning plate 6 is reset to be flush with the upper surface of the lifting plate 5, and is ready for the adhering action of the next group of different specifications of battery packs.

[0059] As shown in Figure 1 The upper surface of the positioning plate 6 is detachably connected with an elastic rubber pad 27.

[0060] In use, the elastic rubber pad 27 can buffer the hard contact between the positioning plate 6 and the bottom of the battery pack, avoid the direct extrusion of the positioning plate 6 on the fragile components such as the pole, pipeline interface and the like at the bottom of the battery pack, prevent the structural damage, and at the same time, enhance the close adhesion of the positioning plate 6 and the battery pack, increase the friction force by the rubber material, and prevent the battery pack from sliding when the vehicle body 1 moves or starts and stops.

[0061] As shown in Figure 1 , Figure 5 The two ends of the positioning plate 6 are provided with elastic supporting rollers 28.

[0062] In use, when the battery pack is attached to the positioning plate 6, the elastic supporting roller 28 first contacts the bottom of the battery pack, and the power of the hydraulic lifting mechanism cannot overcome the elastic force of the elastic supporting roller 28, so that a gap is formed between the positioning plate 6 and the battery pack. After the lifting plate 5 is started to lift, the weight of the battery pack acts on the elastic supporting roller 28, causing it to deform further. At this time, the bottom of the battery pack is in close contact with the upper surface of the positioning plate 6 under the action of gravity, and the deformation of the elastic supporting roller 28 can compensate for the gap between the positioning plate 6 and the bottom of the battery pack. At the same time, the elastic supporting roller 28 can buffer the shaking of the battery pack through its own elasticity, ensuring that the battery pack is always stably attached to the positioning plate 6 during transportation, avoiding displacement or tilting.

[0063] In the same batch of battery pack handling scenarios, the positioning plate 6 does not need to be reset and moved down again. When the forks 2 move directly below the battery pack, due to the possible slight shape difference of the bottom of the battery pack, such as local slight protrusions or depressions, the elastic supporting rollers 28 at both ends of the positioning plate 6 first contact the bottom of the battery pack. Since the height of the positioning plate 6 is lower than the height of the lower surface of the battery pack, the positioning plate 6 can avoid being blocked when moving horizontally. By virtue of its deformable property, when the lifting plate 5 is lifted, the elastic supporting roller 28 will deform adaptively when it is pressed, avoiding the protruding parts of the bottom of the battery pack or filling the gap of the depressions, until each group of positioning plates 6 moves to the lifting position that is suitable for the batch of battery packs. The elastic supporting roller 28 stops deforming because it is no longer subjected to additional pressure.

[0064] In use, the vehicle body 1 of the AGV trolley is moved as a whole to the preset parking area of the battery pack to be transported, and the electric track 3 at the top of the vehicle body 1 is started to drive the forks 2 to extend horizontally along the track direction until the front end of the forks 2 gradually approaches the bottom of the battery pack.

[0065] During the extension of the forks 2, the rear end of the forks 2 presses the movable end of the multi-stage gas supply cylinder 7 through the pressing plate 9, causing the multi-stage gas supply cylinder 7 to contract. The high-pressure gas filled in the multi-stage gas supply cylinder 7 is further compressed due to the reduction in volume, causing the pressure to rise, thereby reserving power for subsequent triggering of the pressing valve 8. At the same time, the universal caster 4 at the front end of the bottom of the forks 2 moves synchronously with the forks 2, assisting in supporting the weight of the forks 2 after extension, avoiding the forks 2 from sagging, shaking or deviating due to overextension, and ensuring that the forks 2 always extend smoothly in the horizontal direction.

[0066] When the forks 2 extend to the preset position and are located directly below the battery pack to be transported, the pressure of the forks 2 on the multi-stage gas supply cylinder 7 reaches a threshold value, the pressing plate 9 is in complete contact with the pressing valve 8 on one side of the multi-stage gas supply cylinder 7, and the pressing valve 8 is triggered to open. At this time, the high-pressure gas compressed in the multi-stage gas supply cylinder 7 is directed to the gas-liquid drive assembly on the vehicle body 1 through the pipeline connected to the pressing valve 8, providing a power source for subsequent attachment of the positioning plate 6 and lifting of the lifting plate 5.

[0067] After the gas-liquid driving assembly receives high-pressure gas, the high-pressure gas first enters the inside of the cylinder 10. Because the force receiving area and the movement resistance of the driving plate 12 are smaller than the starting resistance of the gas pressure lifting structure, the high-pressure gas acts on the lower surface of the driving plate 12 at the lower end of the hydraulic cylinder 11, pushes the driving plate 12 to seal and slide upward along the inner wall of the hydraulic cylinder 11, and compresses and extrudes the spring 13 to store elastic force. The upward movement of the driving plate 12 extrudes the hydraulic oil in the hydraulic cylinder 11, and the hydraulic oil is transported to the hydraulic lifting structure through the oil supply pipeline with a one-way valve;

[0068] The hydraulic oil enters the piston cavity 23 in the piston rod 20, pushes the sealing plate 24 to slide upward against the elastic force of the second reset spring 25, and drives the driving rod 22 and the positioning plate 6 at the top end to move upward synchronously. Because the positioning plate 6 is designed in a distributed manner, it can move upward according to the differences in the non-flat structure at the bottom of the battery pack. The positioning plate 6 corresponding to the protruding area at the bottom first contacts the protruding surface and stops moving upward due to the restriction of the reaction force. The positioning plate 6 corresponding to the recessed area continues to move upward until the upper surfaces of all the positioning plates 6 are tightly attached to different areas at the bottom of the battery pack and the force on each group of positioning plates 6 is balanced, thereby completing the adaptive positioning and preliminary support of the battery pack;

[0069] During this process, the elastic support rollers 28 at both ends of the positioning plate 6 first contact the bottom of the battery pack, forming a temporary gap between the positioning plate 6 and the battery pack to avoid damage to fragile components such as the battery pack bottom pole and pipeline interface due to hard contact;

[0070] When all the positioning plates 6 are completely attached to the bottom of the battery pack, the positioning plate 6 is restricted from further upward movement by the reaction force of the weight of the battery pack itself, and the hydraulic oil in the hydraulic cylinder 11 cannot continue to flow out, and the driving plate 12 is reversely limited by the hydraulic oil. At this time, the pressure of the high-pressure gas in the cylinder 10 continues to rise, and when the pressure exceeds the starting threshold of the gas supply pipeline with a one-way valve, the high-pressure gas is directionally transported to the gas cylinder 18 of the gas pressure lifting structure along the gas supply pipeline. The high-pressure gas pushes the piston plate 19 in the gas cylinder 18 to slide upward against the elastic force of the first reset spring 21, and the piston plate 19 drives the piston rod 20 and the lifting plate 5 at the top end to move upward synchronously. The upward movement of the lifting plate 5 drives the battery pack to move upward synchronously through the attached positioning plate 6, until the bottom of the battery pack is completely separated from the original parking plate, and a safety gap is reserved between the bottom and the parking plate. At this time, the pressure in the gas cylinder 18 and the elastic force of the first reset spring 21 reach a dynamic balance, and the lifting action stops;

[0071] During this process, the weight of the battery pack acts on the elastic support rollers 28, causing them to deform further and compensate for the gap between the positioning plate 6 and the bottom of the battery pack. At the same time, the elastic buffer ensures the stability of the battery pack;

[0072] After the battery pack is lifted into place, the electric track 3 is started to drive the fork 2 to retreat horizontally along the track after the horizontal reset, and the extrusion plate 9 is in contact with the pressing valve 8 during the retreat of the fork 2, the pressing valve 8 is closed under the action of the self-reset structure, cutting off the gas passage between the multi-stage gas supply cylinder 7 and the cylinder 10, when the fork 2 retreats to the appropriate area above the vehicle body 1, the extrusion plate 9 is in complete contact with the valve rod of the first multi-way valve 15, triggering the first multi-way valve 15 to open, the high-pressure gas stored in the cylinder 18 before is returned to the multi-stage gas supply cylinder 7 through the return gas pipeline and the first multi-way valve 15, to supplement the gas of the multi-stage gas supply cylinder 7, to restore its initial high-pressure state, to realize power recovery and reuse, as the gas pressure in the cylinder 18 decreases, the piston plate 19, the piston rod 20 and the lifting plate 5 are stably lowered under the weight of the battery pack and the elastic force of the first reset spring 21, until the lifting plate 5 falls back to the safe height, at this time the hydraulic lifting structure is pressure-kept by the one-way valve of the oil supply pipeline, and the positioning plate 6 still keeps close contact with the bottom of the battery pack, to avoid the deviation of the battery pack;

[0073] After the lifting plate 5 is lowered into place, the moving function of the vehicle body 1 is started to transfer the battery pack to the target storage position along the preset path, during the whole transfer process, the positioning plate 6 ensures that the battery pack does not slide and tilt through the friction force of the elastic rubber pad 27 and the buffering effect of the elastic support roller 28;

[0074] After the vehicle body 1 reaches the specified position, the battery pack is taken away from the positioning plate 6 by a manual or mechanical arm; because the hydraulic lifting structure is still in the pressure-keeping state, the positioning plate 6 keeps the height suitable for the battery pack of this specification, directly driving the vehicle body 1 to move to the parking area of the next battery pack of the same specification, saving the step of self-adaptive fitting of the positioning plate 6 and shortening the handling cycle;

[0075] When it is necessary to switch to handle different specifications of battery packs, after the battery pack is unloaded, the electric track 3 is continued to be started to drive the fork 2 to retreat extra distance away from the battery to be handled, during the retreat of the fork 2, the extrusion plate 9 is in contact with and extrudes the valve rod of the second multi-way valve 16, triggering the second multi-way valve 16 to open, the hydraulic oil in the piston cavity 23 of the hydraulic lifting structure returns to the hydraulic cylinder 11 through the oil return pipeline and the second multi-way valve 16 under the action of the pressure difference and the elastic force of the second reset spring 25, to supplement the hydraulic oil reserve, as the hydraulic oil returns, the sealing plate 24, the driving rod 22 and the positioning plate 6 are synchronously lowered, until the positioning plate 6 is flush with the upper surface of the lifting plate 5, to restore the initial reference height, the electric track 3 is started to drive the fork 2 to move forward, so that the extrusion plate 9 is separated from the contact with the valve rod of the second multi-way valve 16 and the first multi-way valve 15, the two groups of multi-way valves are closed, the gas-liquid circuit is sealed, the vehicle body 1 is driven to move to the parking area of the new specification battery pack, to ensure that the positioning plate 6 is started to fit from the same reference height when handling the new specification battery pack, to avoid the support deviation.

[0076] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A fork truck type AGV cart for carrying a battery pack, characterized by, The utility model provides a kind of truck, including car body (1), and the fork (2) being arranged above car body (1), the fork (2) is connected with the top of car body (1) by electric track (3), the fork (2) front end bottom installs universal trundle (4), lifting plate (5) is arranged above the fork (2), and the lifting plate (5) is connected with the fork (2) between air pressure lifting structure, the lifting plate (5) is distributed with several groups of positioning plate (6) on it, and the positioning plate (6) is connected with the lifting plate (5) between hydraulic lifting structure, the fork (2) rear end is connected with car body (1) by multistage gas supply cylinder (7), multistage gas supply cylinder (7) one side is equipped with with multistage gas supply cylinder (7) intercommunication press valve (8), the end above of car body (1) away from universal trundle (4) is connected with with press valve (8) intercommunication gas-liquid drive assembly, and gas-liquid drive assembly is communicated with air pressure lifting structure, hydraulic lifting structure respectively by pipeline.

2. The fork truck AGV cart for carrying a battery pack according to claim 1, wherein, The multistage gas supply cylinder (7) is filled with high-pressure gas, and the movable end of the multistage gas supply cylinder (7) is connected with the rear end of the fork (2) through the extrusion plate (9), and the extrusion plate (9) corresponds to the press valve (8).

3. The fork truck AGV cart for handling battery packs of claim 2, wherein, The gas-liquid drive assembly includes a cylinder (10) vertically arranged on the car body (1), the upper end of the cylinder (10) is fixedly connected with a vertically arranged hydraulic cylinder (11), the lower end of the hydraulic cylinder (11) is in communication with the inside of the cylinder (10), the lower end of the hydraulic cylinder (11) is sealingly and slidably connected with a driving plate (12), the extrusion spring (13) is fixedly connected between the driving plate (12) and the inner wall of the hydraulic cylinder (11), the hydraulic cylinder (11) is filled with hydraulic oil, the cylinder (10) is in communication with the press valve (8) through the air inlet joint (14) and the pipeline, the air pressure lifting structure is in communication with the cylinder (10) through the air supply pipeline with a one-way valve, and the hydraulic cylinder (11) is in communication with the hydraulic lifting structure through the oil supply pipeline with a one-way valve.

4. The fork truck AGV cart for handling battery packs of claim 3, wherein, One side of the cylinder (10) is provided with a horizontally arranged first multi-way valve (15), and the valve rod of the first multi-way valve (15) corresponds to the extrusion plate (9); the air pressure lifting structure is in communication with the first multi-way valve (15) through the air return pipeline, and the air outlet end of the first multi-way valve (15) is in communication with the multistage gas supply cylinder (7) through the pipeline.

5. The fork truck AGV cart for handling battery packs of claim 4, wherein, The second multi-way valve (16) is horizontally arranged behind the side of the first multi-way valve (15) away from the fork (2), and the valve rod of the second multi-way valve (16) corresponds to the extrusion plate (9); the hydraulic lifting structure is in communication with the liquid inlet end of the second multi-way valve (16) through the oil return pipeline, and the liquid outlet end of the second multi-way valve (16) is in communication with the hydraulic cylinder (11) through the pipeline.

6. The fork truck AGV cart for handling battery packs of claim 5, wherein, The air pressure lifting structure comprises a plurality of groups of mounting holes (17) arranged on the forks (2), the mounting holes (17) are fixedly connected with air cylinders (18), the air cylinders (18) are sealingly and slidably connected with piston plates (19), the upper surfaces of the piston plates (19) are fixedly connected with vertically arranged piston rods (20), the first reset springs (21) are fixedly connected between the upper surfaces of the piston plates (19) and the inner walls of the air cylinders (18), the upper ends of the piston rods (20) are fixedly connected with the lower surface of the lifting plate (5), and the air cylinders (18) are communicated with the barrel (10) through air supply pipelines provided with one-way valves.

7. The fork truck AGV cart for handling battery packs of claim 6, wherein, The hydraulic lifting structure comprises a plurality of groups of driving rods (22) corresponding to the piston rods (20), the upper ends of the driving rods (22) are fixedly connected with the lower surface of the positioning plate (6), the piston rods (20) are provided with piston cavities (23), the piston cavities (23) are sealingly and slidably connected with sealing plates (24), and the second reset springs (25) are fixedly connected between the lower surfaces of the sealing plates (24) and the inner walls of the piston cavities (23). The upper surface of the lifting plate (5) is provided with a sliding hole (26) communicated with the inside of the piston cavity (23), the lower ends of the driving rods (22) pass through the sliding hole (26) and are fixedly connected with the upper surfaces of the sealing plates (24), and the piston cavities (23) are communicated with the hydraulic cylinders (11) through oil supply pipelines provided with one-way valves.

8. The fork truck AGV cart for handling battery packs of claim 7, wherein, The upper surfaces of the positioning plates (6) are detachably connected with elastic rubber pads (27).

9. The fork truck AGV cart for handling battery packs of claim 8, wherein, The two ends of the positioning plates (6) are provided with elastic supporting rollers (28).

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